1. Field of the Invention
This invention relates generally to a system and method for identifying a reliable vehicle in a vehicle-to-vehicle communications system and, more particularly, to a system and method for assuring that information received from a vehicle in a vehicle-to-vehicle communication system is reliable and not malicious.
2. Discussion of the Related Art
Traffic accidents and roadway congestion are significant problems for vehicle travel. Vehicular ad-hoc network based active safety and driver assistance systems are known that allow a vehicle communications system to transmit messages to other vehicles in a particular area with warning messages about dangerous road conditions, driving events, accidents, etc. In these systems, multi-hop geocast routing protocols, known to those skilled in the art, are commonly used to extend the reachability of the warning messages, i.e., to deliver active messages to vehicles that may be a few kilometers away from the road condition, as a one-time multi-hop transmission process. In other words, an initial message advising drivers of a potential hazardous road condition is transferred from vehicle to vehicle using the geocast routing protocol so that vehicles a significant distance away will receive the messages because one vehicle's transmission distance is typically relatively short.
Vehicle-to-vehicle and vehicle-to-infrastructure applications require a minimum of one entity to send information to another entity. For example, many vehicle-to-vehicle safety applications can be executed on one vehicle by simply receiving broadcast messages from a neighboring vehicle. These messages are not directed to any specific vehicle, but are meant to be shared with a vehicle population to support the safety application. In these types of applications, where collision avoidance is desirable, as two or more vehicles talk to each other and a collision becomes probable, the vehicle systems can warn the vehicle drivers, or possibly take evasive action for the driver, such as applying the brakes. Likewise, traffic control units can observe the broadcast of information and generate statistics on traffic flow through a given intersection or roadway. Once a vehicle broadcasts a message, any consumer of the message could be unknown.
It is generally necessary that the information received from a vehicle in these types of vehicle-to-vehicle communications system be reliable to ensure that the vehicle is not attempting to broadcast malicious information that could result in harmful activity, such as a vehicle collision. One current solution for providing trust of the information broadcasted is by transmitting public keys, referred to as public key infrastructure (PKI), so that a vehicle that transmits a certain key is identified as a trusted source. However, transmitting a key between vehicles for identification purposes has a number of drawbacks particularly in system scalability. For example, the number of vehicles that may participate in a vehicle-to-vehicle communications system could exceed 250,000,000 vehicles in the United States alone. Also, the transmission of the key has limitations as to its timeliness of access to the PKI while on the road, the availability of the PKI from anywhere, the bandwidth to the PKI for simultaneous access and the computations needed for PKI certification, reissuance, etc.